Damper winding



July 14, 1925.

R. A. M CARTY DAMPER WINDING Filed Nov. 5. 1923 INVENTOR RoyA./7-"Car7fy B! M ATTbRNEY WITNESSES:

% "M RMQQM Patented July 14-, 1925..

, 1,545,673 PATENT QFFICE.

nor a; masonry, or 'wrnnmsnoae,

PENNSYLVANIA, ASSIGNOB- T0 WESTINGHOUSE ELECTRIU;& MANUFACTURING-COMPANY, A CORPORATION OF PENNSYLVANIA.

DAMPER WINDING.

Application filed November 5, 1923. Serial No. 672,884.

provided with short-circuited damper wind-' ings or starting windings.

a machine of the above-described character having a rotating fieldmember provided with an improved cage winding which shall be of anelectrically eflioient and mechanically strong construction and -whichshall permit the disassembly of the rotor without mg. a

Another object of my invention is to provide a damper winding formachines of the above-descm (1 character com rising a plurality ofintegral groups of, amping condestroying or damaging the damperwindductors and detachable, unitary short-circuiting members foreffecting a short-circuiting connection between the individual groups.

A still further object of my invention is to so supportthe damperwinding upon the' rotor as to secure the same aga nstexcessive strainsimposed thereon by centrifugal force, while providing also a argleradiating surface for dissipating the eat generated in the winding.

The damper windings of synchronous machines, while in themselves simpleand not complicated elements of the machines, must conform to certainvery definite requirements in order to perform satisfactorily thefunctions for which they are designed. The electrical resistance of thewinding must, for certain conditions, be low and the-heatradiatingsurface must be suificientto d1ssipate theheat generated in the windingsby the dampin currents flowing therein. Since the co rifugal forceexerted upon the winding, especially in. cases of high speed machines,may assume large values,

particularcare must be taken also to avoid the addition of unnecessaryweight to the,

winding and to make the same mechanically strong.

Improvement on both sides of improved mechanically and It is alsodesirable that the salient pole members of such machinesshall be easilydetached and disassembled without destroying or seriously damaging thedam er winding. In prior structures, it has en proposed to secure theconducting damper bars,

which are embedded in the pole faces of the polar projections, toshort-ci'rcuiting rings the rotor, by means of screw bolts. Suchconstructions are not very dc sirable since, on account of the size ofthe conductor, the screw bolts are necessarily I I small in diameter andgive thus only a small One object of my invention is to provide degreeof mechanical security, while adding exerted thereupon.

I have found that the performance of the damper winding may be,considerably electrically, without sacrificing any advantages in respectto the ease of. disassembly of the rotor. To this end I provide for.each pole member, a separate damping group consisting of individualconductors embedded in. the pole face and a pair of short-circuit.- ingsegments which are welded or brazed to the conductors on both} sidesfthereof. Each damping group thus constitutes an integral dampingelement of high conductivity and of a mechanically strong structure. Theindividual damping groups are short-circuited by means of speciallyconstructed unitary short-circuiting rings which are clamped thereto bymeans of a relatively small number of easily detachable screws,

. thus permitting the disassembly of the rotor without thedestruction'of the winding.

With the foregoing and other objects in view, my invention consists ofthe arrangements and details of construction hereinafter described andclaimed and illustrated in the'accompanying drawing, wherein Figure 1 isa view in elevation of a portion of a salient-pole rotor member of adynamo-electric machine provided with a damper winding constructed inaccordance with my invention;

Fig. 2 is a sectional view of a pole member illustrated in Fig. 1 takenalong the line II-.II thereof; and

Figs..3 and 4 are similar views illustratin modifications of myinvention.

Tn Figs. 1 and 2 is shown a rotating field member of a dynamo-electricmachine, comprojections areprovided'with axially-extending, partiallyclosed slots 9, in which -are.embeddedconductor members 10 projectingbeyond both ends of the slots. It will be noted that the upper portionsof the end plates tare provided with fingers 11 forholding'and clampingtogether-the slotted part of the laminations.v 1

Short-circuiting segments'12, of angular cross-section, are provided onboth sides of the end plates 4 1n such manner as to support the damperstructure and at the same each polarprojection'and have shoulders 13hearing against projecting portions 14 of time allow for expansion of.the damper bars 10 when they are heated. The outer peripheral surfaces15 of the short-circuiting segments are so arranged as to be alined withthe under surfaces of the projecting damping conductors "10. Theconductors 10 are 'welded or brazed to theshort-circuiting segments attheir contactingsurface 15 and thus constitute a unitary structure ofhighconductivity which is self-supporting witln out the need ofadditional fastening, bolts. A short-circuiting ring 16 is mountedwithin the cylindrical space which is bounded by the angularshort-circuiting segments 12, the cross section of the ring beingsubstantially rectangular and fitting into the rectangular spaceenclosed between the two arms of the angular short-circuiting segments.T The ring makes contact with the entireinner surface 17 of theshort-circuiting segments, thereby assuring a perfect and reliableelectrical contact. The rings 16 are furthermore clamped by means ofbolts 18 to the individual segments and constitute the short-circuitingconnection between the segments, thus completing the damper winding.

By means of my construction, the indlvrdual dampinggroups and thedamping winding as a Whole, have a maximum of conductivity and,therefore, a maximum of efi'ectiveness, which is obtained without-theuse ofan excessive number of bolts and, at the same time, the readilydetachable shortcirculting rings 16 do not interfere with thedisassembly of the rotor member. By means-of my construction, I alsoobtain a high degree of mechanical strength while providing a maximumradiating surface for dlssipating the heat generated in the winding,since most of the surface of the damperwinding structure is indirectcontact with the air and moves in the same. a

In Fig. 3 is shown a modification of my invention in which the shortcircuiting ring 19 is not made solid in cross. section, butfinstead, isa helically wound copper strap conductor 20. The copper strap preferablyhas a small thickness and a fairly great depth for increasing itsmechanical strength 1n the direction 1n which it 1s exposed to excessivecentrifugal forces.

V The coils or 5 layers of the short-circuiting ring may be riveted orwelded together, and I may also or mechanical strength. The mechanicalstrength of the ring 19 is suflicent to withstand the stresses in theunsupported portion between the individual poles, while aflordingliberal radiating surfaces for dissipating the heat generated in thewinding.

In Fig. at is shown a modification of m invention comprising a somewhatsimplified construction which is employed in medium speed machines.ductors10 are welded or brazed to short- The short-circutingconcircuiting segmentsg23 ofangular form. On

account of the lower speed at which the construction is operated, Idispense with the shoulders 13 used in the constructions illustrated inFigs. 2 and 3, obtaining thereby a cheaper unit. A metallic ring 24 isclamped to the individual segments 23'by means of bolts 18 andshort-circuits the individual damping groups upon the several polemembers.

My invention is susceptible of various other modifications and changesand I desire. therefore, that only such limitations shallbe placedthereupon as are imposed by the prior art or set forth in the appendedclaims. 4

I claim as my invention:

1. In a dynamo-electric machine, a rotor member comprising a centralbody portion, a plurality of detachable polar projections secured tosaid central body portion, axially disposed conductors in the pole facesof said polar pro ections, a pair of short-circu ting segments for eachpolar projection, said segments being integrally united with the endportions of said conductors, a pair of continuous annularshort-circuiting members-disposed on both sides. of said rotorrespectively, and means for detachably clamping said short-circuitingsex;

' posed toward said end merits to said annular short-circuiting members.

2. In a dynamo-electric machine, a rotor member comprising a centralbody portion, a plurality of detachable pdlar projections secured tosaid central body portion, each projection being provided on both sidesthereof, with end plates having at their outer ends outwardly projectinglips, shortcircuiting segments of angular cross-section for each side ofeach polar projection, one side of said angular segments being displatesand provided with a projecting member bearing outwardly against saidlips, the other side of said segments being in contact with the endportions of said conductors and integrally united thereto for shortcircuiting the same, unitary continuous short-circuiting rings fittinginto the circular spaces bounded by said segments and means fordetachably clamping said rings to said segments. 7

3.111 a dynamo-electric machine, a rotor member comprising a centralbody portion, a plurality of detachable polar projections secured tosaid central body portion, each projection being provided on both sidesthereof, with end plates having at their outer ends outwardly projectinglips, short circuiting segments of angular cross-section for each sideof each polar projection, one

side of said angular segments being disposed toward said end lates andsecured to the same, the other si e of said segments beingin contactwith the end portions of said-conductors and integrally united thereto,for short-circuiting the same, unitary short-circuiting rings fittinginto the circular spaces bounded by said segments, the cross section ofsaid rings being such as to fit into the angular spaces of said segmentsand make contact over the entire surface of the same, and detachablemeans for clamping said rings to said segments.

,4. A rotating field member for a dynamo-electric machine, comprising asalientpole core member, field-magnet coils thereon, the salient polemembers having overhanging pole-face members thereon, a damper unit oneach salient-pole member comprising conductor bars embedded in thepole-face portion thereof and a short-circuiting segmental memberpermanently united to the ends of said bars on each end of the,salient-pole member, and continuous short-circuiting rings detachablyunited to the respective short-circuiting members of all of thesalient-pole members at each end of said rotating field member.

In testimony wliereof, I have hereunto subscribed my name this th day ofOctober 1923.

ROY A. McCARTY.

